This invention is concerned with the process for removal of molybdenum from a tungsten-containing solution during the manufacture of ammonium paratungstate. A sulfide is added to the tungsten-containing solution which is then acidified to precipitate molybdenum sulfide which can then be removed by filtering, all as disclosed in U.S. Pat. Nos. 3,173,754, 3,939,245 and 4,115,513.